Audible alert signal for an electronic flash unit

ABSTRACT

A circuit in an electronic flash unit including an audio oscillator for providing an audible alert signal to indicate the &#39;&#39;&#39;&#39;ready&#39;&#39;&#39;&#39; state of the flash unit.

United States Patent [1 1 1111 3,778,672 Fountain Dec. 11, 1973 AUDIBLEALERT SIGNAL FOR AN ELECTRONIC FLASH UNIT [56] References Cited [75]Inventor: Gerald F. Fountain, Santa Monica, UNITED T S TENTS Calif-3,011,094 11/1961 Kapteyn 315/133 x Assigneez Ponder & Best, Inc. L08 g3,624,628 ll/l97l Schmidt 33l/65 X Cahf Primary Examiner-Herman KarlSaalbach [22] Filed: July 27, 1972 Assistant Examiner-James B. Mullins[2 Appl No 275 690 Att0rneyCharles G. Lyon et al.

[57] ABSTRACT [52] Cl 315/133 73; A circuit in an electronic flash unitincluding an audio Int Cl H05b 37/02 oscillator for providing an audiblealert signal to indi- [58] Field Olsen c1 31371 29 133 135 cm the readyState of the flash Z v ya? i 29 b4 Z7 I .3; a 27 a l 18 Claims, 1Drawing Figure AUDIBLE ALERT SIGNAL FOR AN ELECTRONIC FLASH UNITBACKGROUND OF THE INVENTION This invention relates to an audible alertsignal utilized in electronic flash units normally associated with thephotographic arts.

Electronic flash units typically include a flash device such as Xenondischarge tube, a storage means such as a storage capacitor connectedacross the discharge tube and triggering circuitry to fire the dischargetube. Once the discharge tube is fired, the storage capacitor isdischarged and a recycle time must expire before the storage capacitoris again at a sufficient potential to aid in a subsequent firing of thedischarge tube. The user of the electronic flash unit, usually a cameraoperator, must be alerted that a proper recycle time has expired toallow the flash unit to be in a ready" state.

In the past, visual alert signals have been utilized to alert the cameraoperator that the electronic flash unit is capable of producing a flash.Visual alert signals usually employ a neon bulb which is activated whenthe storage capacitor is at a sufficient potential to aid in the firingof a discharge tube. A visual alert signal is typically difficult toobserve in that the camera operator must search for this visual signalby taking his eyes off the camera and camera view finder in order toscan the companion electronic flash unit for a visual indication.

Visual alert signals create a further problem in that the cameraoperator is likely to be in a variety of lighting conditions and, assuch, the condition of the visual signal of bulb may not be readilyapparent.

The foregoing problems have been substantially eliminated by providingin a preferred embodiment of my invention a circuit which provides anaudible alert signal of a limited duration to alert the camera operatorthat the associated flash unit is in a ready state. This audible alertsignal allows the camera operator to give full visual attention to thecamera and camera view finder and can enable a lessening of picturestaken when the flash unit is not in the ready state.

SUMMARY OF THE INVENTION It is an object of this invention to provide anaudible alert signal for an electronic flash unit.

It is another object of this invention to provide an audible alertsignal for an electronic flash unit which will be of a limited duration.

It is a further object of this invention to provide an audible alertsignal of limited duration which will be used in combination with avisual alert signal.

Briefly stated, and according to one aspect of my invention, theforegoing objects are achieved by producing an electronic flash unitutilizing an audible alert signal in theform of an audio oscillator or abuzzer to produce an audible alert signal of a limited duration. Thisaudible signal will allow a camera operator to know if his or herassociated flash unit is in a ready state.

BRIEF DESCRIPTION OF THE DRAWING The invention both as to itsorganization and principle of operation, together with further objectsand advantages thereof, may better be understood by reference to thefollowing detailed description of an embodiment of the invention whentaken in conjunction with the accompanying drawing.

The drawing is a circuit diagram illustrating an exemplary embodiment ofthe basic concepts of a flash unit comprising an audible alert signal inthe form of an audio oscillator in conjunction with a visual alertsignal in the form of a neon bulb in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,there is shown a flash unit 11 enclosed in dotted lines which includes aflash device or xenon discharge tube 12 with principal electrodes l3 and14 included therein. Principal electrode 13 is connected to an upperconductor 15 and principal electrode 14 is connected to a lowerconductor 16. The flash unit 11 receives its energization from anysuitable source of potential (not shown) connected to terminals 17 and18 of conductor 15 and 16 respectively.

As is well known in the art, triggering circuitry for a flash unitincludes a step up triggering coil or transformer 19 having a primarycoil 20 and a secondary coil 21 to trigger the discharge tube 12 througha trigger electrode 22 when required. The trigger electrode 22 may beeither within or outside of the discharge tube 12. Resistor 23 isconducted between upper conductor 15 and capacitor 24. Capacitor 24 isconnected at its other end to lower conductor 16. Transformer 19,resistor 23 and capacitor 24 comprise triggering circuitry normally usedin flash units.

Primary coil 20 of transformer 19 receives its excitation when anormally open switch 25, which is responsive to a shutter switch of anassociated camera, is closed. This allows capacitor 24 to dischargeacross primary winding 20 thereby activating transformer T9 and triggerelectrode 22 which triggers discharge tube 12.

Connected across discharge tube 12 is a signal storage means or storagecapacitor 26 which will receive its energization from the source (notshown) applied at terminals 17 and 18. Capacitor 26, when fully charged,will not fire discharge tube 12, but will apply a voltage to thedischarge tube 12 equal to its charged value. The voltage from thecharged capacitor 26 and the triggering of the discharge tube 112through trigger electrode 22, when switch 25 is closed, causes thedischarge tube 12 to fire.

In order to provide in this embodiment the addition of a visual alertsignal, resistor 27 and a visual alert signal means, such as a gas tubeor a neon bulb 28, are serially connected in upper conductor 15 betweenone end of capacitor 26 and circuitry 29, to be described later. The gasin neon bulb 28 prevents current from travelling to an audible signalmeans, such as a buzzer, or circuitry 29 until an ignition voltage levelor firing voltage is achieved across neon bulb 28. Once this firingvoltage is achieved, the gas in neon bulb 28 ionizes or ignites andilluminates thereby providing a visual indication.

The firing voltage of neon bulb 28 is reached when storage capacitor 26reaches a voltage level capable of firing discharge tube 12 whentriggered by the voltage applied to trigger electrode 22. Resistor 27determines the firing voltage of neon bulb 28.

In order to provide an audible alert signal when storage capacitor 26 iscapable of providing its required voltage to discharge tube 12, audiblesignal means or circuitry 29 is provided. The conducting neon bulb 28establishes a voltage at a point A between the neon 3 bulb 28 in flashunit ill and capacitor 30. In circuitry 29, capacitor 30 is connectedbetween upper conductor a and lower conductor 16 to allow a slow rise inthe voltage established at a point A as capacitor 30 charges.

Neon bulb 28 is further connected to circuitry 29 through resistor 31 tothe base of transistor 32. Transistor 32 is connected in a manner wellknown in the art to a ceramic transducer element 33 to form an audiooscillator. For illustration, transistor 32 is shown to be an NPNtransistor, and an audio oscillator utilizing a PNP transistorconfiguration with a ceramic transducer element will be apparent tothose skilled in the art. Transistor 32 and the ceramic transducerelement 33 will oscillate in the audible range, and in this preferredembodiment at a value approximating 2 kHz.

As is well known in the art, the unique configuration and resonancecharacteristics of the ceramic transducer element 33 to allow adequatephase relationships to transistor 32 will cause audio oscillation whenproperly biased. Transistor 32 receives its bias voltage from a biassource (not shown) applied between terminals 34 and 35 of upperconductor 15b and lower conductor 16 respectively. This bias source isapplied to the emitter of transistor 32 from terminal 35 throughresistor-36 and ceramic transducer element 33. This bias source is alsoapplied to the collector of transistor 32 through a variable resistor 37which is varied to adjust the time duration of the audible signal.

Resistor 38 is connected between variable resistor 37 and terminal 34,and capacitor 39 is connected at one end between variable resistor 37and resistor 38 is connected at the other end to terminal 35 to provideisolation for circuitry 29 in a manner well known in the art.

In operation, switch 25 in flash unit 11 is normally open, and the onlyvoltage applied to discharge tube 12 is that associated with storagecapacitor 26. Storage capacitor 26 is normally not great enough to tiretube 12 and requires switch 25 to be closed (as the shutter of thecamera is closed) to allow the voltage from the triggering circuitryapplied through electrode 22 to fire" discharge tube 12. Once thedischarge tube 112 is fired, the voltage across storage capacitor 26drops drastically due to the low resistance or short circuiting effectof the discharge tube l2. The storage capacitor 26 generally isrecharged after the discharge tube 22 has fired in order to providesufficient voltage to fire" the discharge tube 12 again.

The gas in neon bulb 23 will ignite and illuminate when the voltageacross storage capacitor 26 reaches the ignition voltage level of theneon bulb 28 as determined by series resistor 27.

Once the neon bulb 28 has ignited, and therefore will be conductive,capacitor 30 of circuitry 29 will receive the voltage established byneon bulb 28 and will establish a voltage rise slowly at pont A due tothe charging effect of capacitor 30. Thus, the neon bulb 28 or othersuitable gas tube (with or without a visual display), may be used toestablish a source of voltage when the ionization of the tube occurs.This voltage may be used to activate an audible alert signal.

The increasing voltage appearing at point A is applied to the base oftransistor 32 to allow transistor 32 to be biased on and thus oscillateand produce an audible alert signal in combination with the ceramictransducer element 33 to alert a camera operator that flash unit 11 isready for refiring. Transistor 32 is biased in such a manner thatoscillations will only occur within a narrow range of the forwardvoltage applied to the base of transistor 32. Voltages above or belowthis range will cause oscillations to cease. Since the voltage at pointA has a rising characteristic due to the charging effect of capacitor30, the oscillations caused by transistor 32 and the ceramic transducerelement 33 are only momentary. The length of time of these oscillationswhich will produce the audio signal can be varied by adjusting resistor37 connected to the collector of transistor 32.

It has been shown that by providing a circuit in the form of an audiooscillator comprising a transistor and a ceramic transducer element thatan audible alert signal of a pre-determined duration can be accomplishedto indicate the ready state of a flash unit.

While an embodiment and application of this invention has been shown anddescribed, it will be apparent to those skilled in the art thatmany moremodifications are possible without departing from the inventive conceptsherein described. The invention, therefore, is not to be restrictedexcept as is necessary by the prior art and by the spirit of theappended claims.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

1. An electronic flash unit comprising:

a flash device;

storage means for applying a voltage to said flash device;

circuit means for triggering said flash device and for allowing saidstorage means to apply the voltage to said flash device;

means for producing an audible alert signal of a predetermined durationwhen said storage means is at a voltage level sufficient for applyingthe voltage to said flash device; and

signal means electrically coupled to said audible alert signal means forproviding a signal to said audible alert signal means, said audiblealert signal means being activated during a predetermined portion of thesignal produced by said signal means.

2. An electronic flash unit as in claim 1 wherein the audio alert signalis produced at a frequency of approximately 2 kilohertz.

3. An electronic flash unit as in claim 2 wherein said means forproducing an audible alert signal is an audio oscillator.

4. An electronic flash unit as in claim 3 wherein said audio oscillatoris a single transistor ceramic transducer element audio oscillator.

5. An electronic flash unit as in claim 1 wherein said signal meansprovides a varying signal and said audible alert signal means isactivated only during a predetermined portion of the varying signal.

6. An electronic flash unit as in claim 5 further including a switchingmeans electrically coupled to said signal means and to said means forproducing an audible alert signal, the predetermined portion of thevarying signal of said signal means activating said switching meanswhich in turn activates said means for producing an audible alertsignal.

7. An electronic flash unit as in claim 6 wherein said signal means is acapacitor and thevarying signal is an increasing signal which activatessaid switching means at the beginning of the predetermined portion ofthe varying signal and deactivates said switching means at the end ofthe predetermined portion of said varying signal thereby realizing anaudible alert signal of a predetermined duration.

8. An electronic flash unit comprising:

a flash device;

storage means for applying a voltage to said flash device;

circuit means for triggering said flash device and for allowingdischarge of said storage means into said flash device;

means for producing an audible alert signal when said storage means isat a voltage level sufficient for applying the voltage to said flashdevice;

means for terminating the audible signal after a predetermined duration;and

signal means electrically coupled to said audible alert signal means forproviding a varying signal to said audible alert signal means, saidaudible alert signal being activated a predetermined time delay afterthe varying signal is provided.

9. An electronic flash unit as in claim 8 wherein said means forterminating the audible signal after the predetermined duration includescapacitive means for applying a voltage to said audio alert signal meansthereby terminating the audio alert signal.

10. An electronic flash unit as in claim 8 wherein said means forproducing an audible signal is an audio oscillator and said audiooscillator is a single transistor ceramic transducer element audiooscillator.

11. An electronic flash unit as in claim 8 further including a switchingmeans electrically coupled to said audible alert signal means and tosaid signal means, said switching means having a conductive and anonconductive state, said switching means being in its conductive stateonly when a predetermined portion of the varying signal is appliedthereto, thereby providing the audible alert signal.

12. An electronic flash unit comprising:

a flash device;

storage means for applying a first voltage to said flash device;

circuit means for applying a triggering voltage to said flash device;

means for producing a visual signal when said storage means is at avoltage level sufficient to apply the first voltage to said flashdevice;

means for producing an audible signal of a predetermined duration whensaid storage means is at a voltage level sufficient to apply the firstvoltageto said flash device; and

signal means electrically coupled to said visual signal means and saidaudible signal means for providing a varying signal to said audiblesignal means in response to the visual signal produced by said visualsignal means, a predetermined portion of the varying signal beingcapable of activating said audible signal means.

13. An electronic flash unit including a flash device comprising:

storage means for applying a first voltage to the flash device;

circuit means for applying a triggering voltage to the flash device;

means for producing a visual signal when said storage means is at avoltage level sufficient to apply the first voltage to the flash device;

means for producing an audible signal in response to the production ofthe visual signal;

means for terminating the audible signal after a predetermined time; and

signal means electrically coupled to said visual signal means and saidaudible signal means for providing a varying signal to said audiblesignal means, said varying signal being initiated when said visualsignal means produces the visual signal, the varying signal providing,at a predetermined portion thereof, the activation of said audiblesignal means.

14. An electronic flash unit as in claim 13 wherein said means forproducing a visual signal is a neon bulb.

15. An electronic flash unit comprising:

a flash device;

source means for applying a voltage to said flash device;

circuit means for triggering said flash device and for allowing saidsource means to apply the voltage to said flash device;

a gas tube responsive to said source means and capable of achieving anionization state when said source means is at a voltage level sufficientfor applying the voltage to said flash device;

audible alert signal means responsive to said gas tube for producing anaudible alert signal of a predetermined duration when said gas tubeachieves the ionization state; and

signal means electrically coupled to said gas tube and to said audiblealert signal means for providing a varying signal to said audible alertsignal means, a predetermined portion of the varying signal beingcapable of activating said audible alert signal means.

16. An electronic flash unit as in claim 15 including means forterminating the audible alert signal after a ,pre-determined duration.

17. An electronic flash unit as in claim 15 wherein said gas tube is aneon bulb.

18. An electronic flash unit as in claim 15 wherein said means forproducing the audible alert signal isan audio oscillator.

* a =t= s

1. An electronic flash unit comprising: a flash device; storage meansfor applying a voltage to said flash device; circuit means fortriggering said flash device and for allowing said storage means toapply the voltage to said flash device; means for producing an audiblealert signal of a predetermined duration when said storage means is at avoltage level sufficient for applying the voltage to said flash device;and signal means electrically coupled to said audible alert signal meansfor providing a signal to said audible alert signal means, said audiblealert signal means being activated during a predetermined portion of thesignal produced by said signal means.
 2. An electronic flash unit as inclaim 1 wherein the audio alert signal is produced at a frequency ofapproximately 2 kilohertz.
 3. An electronic flash unit as in claim 2wherein said means for producing an audible alert signal is an audiooscillator.
 4. An electronic flash unit as in claim 3 wherein said audiooscillator is a single transistor ceramic transducer element audiooscillator.
 5. An electronic flash unit as in claim 1 wherein saidsignal means provides a varying signal and said audible alert signalmeans is activated only during a predetermined portion of the varyingsignal.
 6. An electronic flash unit as in claim 5 further including aswitching means electrically coupled to said signal means and to saidmeans for producing an audible alert signal, the predetermined portionof the varying signal of said signal means activating said switchingmeans which in turn activates said means for producing an audible alertsignal.
 7. An electronic flash unit as in claim 6 wherein said signalmeans is a capacitor and the varying signal is an increasing signalwhich activates said switching means at the beginning of thepredetermined portion of the varying signal and deactivates saidswitching means at the end of the predetermined portion of said varyingsignal thereby realizing an audible alert signal of a predeterminedduration.
 8. An electronic flash unit comprising: a flash device;storage means for applying a voltage to said flash device; circuit meansfor triggering said flash device and for allowing discharge of saidstorage means into said flash device; means for producing an audiblealert signal when said storage means is at a voltage level sufficientfor applying the voltage to said flash device; means for terminating theaudible signal after a predetermined duration; and signal meanselectrically coupled to said audible alert signal means for providing avarying signal to said audible alert signal means, said audible alertsignal being activated a predetermined time delay after the varyingsignal is provided.
 9. An electronic flash unit as in claim 8 whereinsaid means for terminating the audible signal after the predeterminedduration includes capacitive means for applying a voltage to said audioalert signal means thereby terminating the audio alert signal.
 10. Anelectronic flash unit as in claim 8 wherein said means for producing anaudible signal is an audio oscillator and said audio oscillator is asingle transistor ceramic transducer element audio oscillator.
 11. Anelectronic flash unit as in claim 8 further including a switching meanselectrically coupled to said audible alert signal means and to saidsignal means, said switching means having a conductive and anonconductive state, said switching means being in its conductive stateonly when a predetermined portion of the varying signal is appliedthereto, thereby providing the audible alert signal.
 12. An electronicflash unit comprising: a flash device; storage means For applying afirst voltage to said flash device; circuit means for applying atriggering voltage to said flash device; means for producing a visualsignal when said storage means is at a voltage level sufficient to applythe first voltage to said flash device; means for producing an audiblesignal of a predetermined duration when said storage means is at avoltage level sufficient to apply the first voltage to said flashdevice; and signal means electrically coupled to said visual signalmeans and said audible signal means for providing a varying signal tosaid audible signal means in response to the visual signal produced bysaid visual signal means, a predetermined portion of the varying signalbeing capable of activating said audible signal means.
 13. An electronicflash unit including a flash device comprising: storage means forapplying a first voltage to the flash device; circuit means for applyinga triggering voltage to the flash device; means for producing a visualsignal when said storage means is at a voltage level sufficient to applythe first voltage to the flash device; means for producing an audiblesignal in response to the production of the visual signal; means forterminating the audible signal after a predetermined time; and signalmeans electrically coupled to said visual signal means and said audiblesignal means for providing a varying signal to said audible signalmeans, said varying signal being initiated when said visual signal meansproduces the visual signal, the varying signal providing, at apredetermined portion thereof, the activation of said audible signalmeans.
 14. An electronic flash unit as in claim 13 wherein said meansfor producing a visual signal is a neon bulb.
 15. An electronic flashunit comprising: a flash device; source means for applying a voltage tosaid flash device; circuit means for triggering said flash device andfor allowing said source means to apply the voltage to said flashdevice; a gas tube responsive to said source means and capable ofachieving an ionization state when said source means is at a voltagelevel sufficient for applying the voltage to said flash device; audiblealert signal means responsive to said gas tube for producing an audiblealert signal of a predetermined duration when said gas tube achieves theionization state; and signal means electrically coupled to said gas tubeand to said audible alert signal means for providing a varying signal tosaid audible alert signal means, a predetermined portion of the varyingsignal being capable of activating said audible alert signal means. 16.An electronic flash unit as in claim 15 including means for terminatingthe audible alert signal after a pre-determined duration.
 17. Anelectronic flash unit as in claim 15 wherein said gas tube is a neonbulb.
 18. An electronic flash unit as in claim 15 wherein said means forproducing the audible alert signal is an audio oscillator.